This invention relates to apparatus for actuating a plurality of probes and a generally planar test member into electrical contact.
Circuit board verifiers are generally known employing an actuator assembly for relatively moving a plurality of electrical test probes and a circuit board, bearing test points, into electrical contact.
The probes are generally elongated, having a probe head at one end for making electrical contact with a test point on the circuit board and an opposite end electrically connected to a test device such as a circuit board analyzer. Continuity and lack of continuity between the various test points on the circuit board are detected by the analyzer through the probes for use in determining if the circuit board is proper or defective.
Various approaches have been utilized for bringing the array of probes and the circuit board under test into engagement. One class of these devices is vacuum actuated. FIG. 12 schematically depicts a cross-sectional view of such a device with the left hand side of the device broken away for simplicity. Referring to FIG. 12, an array of telescoping spring probes are mounted in a fixed backing member 302. One such probe is depicted by way of example at 306. The fixed backing member 302 is generally a rectangular shaped plate which is fixed within a picture frame shaped housing 308.
A stiff backing member 312 of generally the same shape as the fixed backing member 302 is flexibly mounted over the fixed backing member 302 by a spring 314. A diaphragm or sealing member 315 is mounted on the opposite side of the stiff backing member from the fixed backing member. The sealing member is generally rectangular in shape and is fixed around the edge thereof in the picture frame shaped housing 308. A hole is cut through the sealing member 315 and the stiff backing member 312 in alignment with each probe, one such hole 316 being depicted in alignment with probe 306. The circuit board to be tested is depicted at 318 where it is aligned with respect to the probes. A hinged door 320 has a recess into which the circuit board 318 extends allowing a lower sealing edge 320a of the door to form a seal against the sealing member completely around the circuit board. As a result, a vacuum chamber 322 is formed between the door and the fixed backing member and the housing 308. In operation the vacuum chamber 322 is evacuated through port 324 extending through housing 308, drawing the door, the sealing member, the circuit board, and the stiff backing member in the direction of the probes until the probe heads make electrical contact with test points on the circuit board.
The probes are electrically connected by wiring to one of a set of interface pins 307 which in turn are connected by an interface assembly to a data processing apparatus for analyzing the electrical connection for the circuit board through the probes.
Another prior art device which is similar to that depicted in FIG. 12 but eliminates the door is useful for testing a circuit board which does not have holes and can form its own seal against the sealing member. An example of such a circuit board is one where the holes have been filled in by component leads and solder.
Other arrangements have been made for bringing an array of probes and a circuit board together for test. For example, a movable platen has been used for engaging a circuit board with an array of spaced contact probes. However, such arrangements are generally slow and costly.